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[Update (2019-03-08_12:00:00 UTC): Apparently, the NASA channel is rebroadcast on YouTube; no word yet on a separate live stream. --martyb]
Dragon has Docked-But the Real Pucker Moment for SpaceX's Capsule Awaits :
[...] This week after undocking from the station early Friday morning, the spacecraft will burn its thrusters to perform a deorbit burn, essentially slowing its velocity enough to nudge itself out of orbit and begin the process of falling back to Earth. This will occur at around 7:50am ET. Splashdown in the Atlantic Ocean should come at about 8:45am ET.
As the vehicle descends, its speed must slow from a starting point of about 27,000km/hour (~16,777mph) as it steadily encounters thicker atmosphere. Temperatures outside the capsule will exceed those on the surface of the Sun, testing Dragon's heat shield. Rather than breathing fire, Dragon will attempt to survive it.
The two most critical moments will come during entry to Earth's atmosphere and near the end of the descent when Dragon's four main parachutes deploy. At the top of the atmosphere, there is a small chance the vehicle will begin to roll uncontrollably due to Dragon's design, since the capsule is not symmetrical to the placement of engine thrusters. And with Dragon's parachutes—the last critical step to arresting its fall—everything just has to work.
[...] "There's a high pucker factor with re-entry," said Garrett Reisman, a veteran of two space shuttle landings. Still a consultant for SpaceX, Reisman helped lead the design of Dragon for the company from 2011 to 2018. "I'm not saying that I'll be really, really nervous coming home on Friday, but when it finally happens I'll feel really good about it."
Besides great pictures from the launch and through to the docking of Demo-1, there is in-depth discussion of the challenges of using parachutes for the landing as well as the Demo-2 mission's testing of the new emergency escape system.
A story at c|net adds:
NASA kicks off its live coverage on Thursday at 9:15 a.m. PT when the ISS crew is set to close the hatch leading to the capsule. The space agency will later pick up with coverage of the undocking process, which is scheduled to start at 11 p.m. PT Thursday.
Crew Dragon will spend a little time in space before re-entering the atmosphere. NASA TV will track the deorbit and landing starting around 4:30 a.m. PT Friday.
Crew Dragon delivered crew supplies and equipment to the ISS. While no humans were on board, the capsule did host a test dummy named Ripley and a cute Earth plushie toy, which was adopted by NASA astronaut Anne McClain. The capsule will return with research samples on board.
As important as it was for the Demo-1 mission to launch and dock with the ISS, future astronauts would like some assurance they will safely get back to Earth, too.
As of this writing there is no word yet on whether or not this landing will also be live streamed on YouTube; check SpaceX's channel for updates.
(Score: 0) by Anonymous Coward on Thursday March 07 2019, @10:03PM (8 children)
This is just like Apollo, Gemini, and Mercury. We were promised a landing, not a splashdown. What happened here? Even the Russians manage a landing with retro rockets, although they also cheat a bit with a parachute.
Also, where do the parachutes even fit? The top is occupied by a second door. For that matter, why didn't they just use a single door? There is no reason you couldn't enter from the top or dock from the side.
(Score: 5, Insightful) by bob_super on Thursday March 07 2019, @10:13PM (2 children)
> This is just like Apollo, Gemini, and Mercury. We were promised a landing, not a splashdown. What happened here?
NASA happened. SpaceX follows customer specs.
> Even the Russians manage a landing with retro rockets, although they also cheat a bit with a parachute.
Highly wrong. They mostly land with parachutes, with rockets firing at the last second to cushion a bit
It's still a crash over 10 miles per hour, uncomfortable for the riders, not great for capsule reuse.
> Also, where do the parachutes even fit? The top is occupied by a second door.
Turns out they were waiting for your answer, didn't receive it on time, and launched without parachutes after all.
Good news for anyone looking for fabric on Ebay.
> For that matter, why didn't they just use a single door? There is no reason you couldn't enter from the top or dock from the side.
Enter from the top: Gravity 101
dock from the side: did you read the part about worrying about the capsule staying balanced correctly? Turns out it's even harder if you have the docking adapter on one side.
Please inform yourself before ranting.
(Score: 1, Interesting) by Anonymous Coward on Thursday March 07 2019, @10:34PM (1 child)
We have things called ladders. They are used all the time, for example to climb in and out of aircraft. Some aircraft even use them for multiple internal levels.
A docking adapter of known mass and unmoving position is trivial to balance. The difficult problem is loose internal content like supplies and trash.
(Score: 3, Funny) by bob_super on Thursday March 07 2019, @10:52PM
The Russians would like to hire you to explain your concept of ladders, as they keep associating spacecrafts with trampolines.
(Score: 4, Informative) by takyon on Thursday March 07 2019, @10:20PM (3 children)
https://spaceflightnow.com/2017/07/19/propulsive-landings-nixed-from-spacexs-dragon-spaceship/ [spaceflightnow.com]
The splashdown approach works well. It's entirely possible that nobody except for NASA will use Falcon 9 + Crew Dragon 2 to launch astronauts. It would be better to focus on Starship/BFR which will land propulsively.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 0) by Anonymous Coward on Thursday March 07 2019, @10:38PM (2 children)
Saltwater is really corrosive.
Spashdown caused major trouble for reuse of the Space Shuttle boosters. SpaceX has even suffered previously, with the Falcon-1 launching off of a tiny island in the Pacific.
(Score: 2, Insightful) by Sulla on Thursday March 07 2019, @10:45PM
Based on Musk's comments about BFR, I wonder how much he is even concerned about re-usability with the dragon capsule. As long as it works without issue for the next five to ten years, who cares what happens after that.
Ceterum censeo Sinae esse delendam
(Score: 3, Informative) by takyon on Thursday March 07 2019, @10:47PM
SpaceX's plan appears to be to refurbish and reuse the salty crew dragon capsules for cargo launches to the ISS only.
https://www.teslarati.com/spacex-no-crew-dragon-spaceship-reuse-nasa-astronaut-launches/ [teslarati.com]
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 5, Informative) by julian on Thursday March 07 2019, @10:21PM
The chutes attach to the side. [vox-cdn.com]
The Soviets had to use a ground landing system for a couple reasons. Their launch site at Baikonur is landlocked, so for safety purposes any crewed spacecraft launched from there would have to be able to land on solid ground in case of an emergency abort early in launch. The USA has access to oceans on both sides so launching from Florida means an early abort ends up over water. So since NASA had to design a spacecraft that could splashdown anyway, skipping ground landing entirely made sense. We also had (have) a huge navy which could spread out over thousands of kilometers to quickly recover our astronauts, the Soviets didn't.